Prostate Specific Antigen (PSA)
PSA is a blood test that detects proteins produced only by the prostate. When a man has prostate cancer, the gland produces more of the proteins, which are shed into the bloodstream. PSA has helped improve prostate cancer diagnosis and treatment by detecting many more cancers at an early stage when they are most treatable and most likely to be cured. An elevated PSA level does not always indicateprostate cancer: Benign prostatic hyperplasia (non-cancerous enlargement of the prostate gland) also can cause the prostate to produce more PSA.

Digital Rectal Exam (DRE)
Physicians can detect some prostate cancers by means of a DRE, which involves inserting a gloved, lubricated finger into a man's rectum and pressing against the prostate to inspect its surface for any irregularities. The digital rectal exam is used inconjunction with PSA testing.

Transrectal Ultrasound (TRUS)
This test allows a physician to make a picture of the prostate without actually seeing the organ. The image is made by inserting a probe into the rectum and generating sound waves that bounce off the prostate. This information is translated by a computer into an image on a video screen. TRUS typically is used when the PSA or DRE suggests an abnormality of the prostate.

Biopsy
If the prostate appears abnormal by PSA or DRE, small tissue samples are removed by inserting a surgical needle into the prostate, usually guided by ultrasound images. The samples are then analyzed under a microscope. This technique is called fine needle aspiration (FNA). A biopsyis necessary to make a definite cancer diagnosis and to obtain information about the nature of a tumor.

If a biopsy indicates cancer, laboratory analysis can determine how differentiated the cells are, which indicates the cancer's potential to grow and spread to other parts of the body. Well-differentiated cancer closely resembles normal tissue, while poorly differentiated cancer does to a much lesser extent.

Prostate cancer often spreads to the bone. To detect these metastases, doctors will perform tests including a complete blood count (CBC), an alkalinephosphatase test, and a bone scan. A CBC measures the number of red cells, white cells and platelets in the blood. Elevated levels of the enzyme alkaline phosphatase, which is produced by bone and liver tissue, may indicate cancer in these areas.

In a bone scan, an X-ray image of a portion of the skeleton is taken after a radioactive substance is injected into the body. Rapidly dividing cells within the bones will absorb more of the substance, producing dense gray areas, called "hot spots", on the X-rays. These hot spots may indicate the presence of cancerous cells.